1. Field of the Invention
The present invention relates to an electrical outlet cover for enclosing an electrical outlet box.
2. Description of the Related Art
Electrical outlet wall cover plates are common fixtures in most homes and businesses for covering connections to electrical outlets mounted on walls. The connections are made within electrical boxes that are anchored to supports within the walls. Open ends of the boxes are accessible through holes formed in the walls for making the connections to the electrical outlets. The wall plates are mounted on the outlets and cover both the electrical boxes and the access holes that are formed in the walls. One or more openings are formed in the plates to permit receptacles of the electrical outlets to project into front faces of the plates for receiving electrical plugs.
Most wall plates are either stamped out or molded from a material such as plastics, wood or ceramic and are produced in standard sizes and shapes. The most common wall plates are sized to accommodate electrical outlets with duplex receptacles. Similarly sized wall plates are also used to cover connections to a variety of other electrical fixtures including wall switches and communication outlets. The wall plates are attached to wall surfaces with screws.
A problem with current wall plates is that they need to have sufficient strength and stiffness to resist breakage when being screwed to the outlet box and to resist peel-back at the corners. They also need to be mass produced economically. Commonly produced wall plates are composed of urea polymers. These are approximately ten times stiffer than comparable plates made from nylon, however, they are subject to easy breakage. While it would be possible to produce thicker wall plates which would have better breakage and peel-back resistance, such would be economically disadvantageous.
Wall plates having reinforcing ribs are known in the art. See for example, U.S. Pat. Nos. 4,603,932, 5,114,365, and 5,835,980, however, such do not teach linear arrays of cored, rectangular stiffening ribs.
It would be desired to produce an electrical outlet cover for enclosing an electrical outlet box which has enhanced stiffness and prevention of corner twisting while employing a minimum amount of material for a maximum stiffness.
It has now been found that by forming a wall plate having strategically places arrays of ribs on its back side, one can attain a thin plate having a high degree of stiffness. The location of the ribs is important for attaining an advantageous stiffness to weight ratio, i.e. employing a minimum amount of material for a maximum stiffness. The stiffness and prevention of corner twisting can be further enhanced by selectively varying the plate wall thickness, that is by reinforcing the plate material at optimal locations such as around electrical plug passages and the screw hole.
The invention provides an electrical outlet cover for covering an electrical outlet box which comprises:
(a) a generally rectangular plate having front and back surfaces and upper, lower, left and right edges defining corners at the intersection of adjacent edges; said plate having upper and lower electrical plug passages extending through the front surface and back surface;
(b) upper and lower linear arrays of cored, rectangular stiffening ribs projecting outwardly from the back surface of the plate, one array positioned along each of an upper and a lower edge of the plate;
(c) left and right linear arrays of cored, rectangular stiffening ribs projecting outwardly from the back surface of the plate, the left linear array positioned between the electrical plug passages and a left edge of the plate and the right linear array positioned between the electrical plug passages and a right edge of the plate; each of the left and right linear arrays extending from the upper linear array to the lower linear array;
(d) at least one central linear array of cored, rectangular stiffening ribs projecting outwardly from the back surface of the plate positioned between the electrical plug passages and extending from the left linear array to the right linear array;
(e) a reinforced opening for receiving a screw extending through the front surface and back surface of the plate and positioned at the midpoint of the central linear array; and
(f) a plurality of side reinforcing fingers projecting outwardly from the back surface of the plate and extending from the left edge of the plate to the left linear array, and from the right edge to the right linear array.